Although you may just be hearing about "tagging" or "social bookmarking" they have actually been around since 2003. The idea created by Del.icio.us is where you share your favorite sites with other people and tag them with certain keywords. As creating tags become more popular and more people tag the things you have tagged your sites become more popular and you can actually increase your traffic. Think about your computer favorite bookmarks. Think about a big community of people doing this on specific sites and this is the best way to describe social bookmarking. According to Wikipedia "A tag is a keyword which acts like a subject or category. A keyword is used to organize webpages and objects on the Internet. Each user "tags" a webpage or image using his/her own unique tag. An image or webpage may have multiple tags that identify it. Webpages and images with identical tags are then linked together and users may use the tag to search for similar webpages and images. "
With more and more people using the internet for good solid information and content to read social bookmarking is just going to continue to get more popular. Especially when people start to rely less on search results for good content. Communities like Del.icio.us and digg rely on the people inside those communities to find the most popular stuff. SO what does this mean to you? In order for you to really make use of sites like this you need to come up with useful information for the community related to what you do. Just like in the search engines, you will not be able to move up the rankings without good unique content (the cry of every SEO)
The best way to get started and trying to figure out this relatively new concept is just going and doing. Go sign up for an account, look at what other people are doing. See what other people are blogging about in your industry, see what other people are tagging in your industry. See what other people are writing articles about and find the ones that community members really like. Doing this should help you get a better understanding of this idea and already puts you above most people you may be up against since this idea is, like I said fairly new....
Good luck and happy tagging!!